Question: What's the first wrong statement in the proof below that $ \triangle CEF \cong \triangle CEB$ $ \; ?$ $ \overline{BC} $ is parallel to $ \overline{DF} $. This diagram is not drawn to scale. $A$ $B$ $C$ $D$ $E$ $F$ Givens $ \overline{AB} \cong \overline{EF}$ $, \ $ $ \angle BAC \cong \angle CEF$ $, \ $ $ \overline{AC} \cong \overline{CE}$ $, \ $ $ \angle BED \cong \angle CEF$ $, \ $ $ \overline{DE} \cong \overline{CE}$ $, \ $ and $\ $ $ \angle BDE \cong \angle ECF$ Proof $ \triangle CEF \cong \triangle CAB$ because SAS $ \overline{CF} \cong \overline{BC}$ because corresponding parts of congruent triangles are congruent $ \overline{AF} \cong \overline{CF}$ because corresponding parts of congruent triangles are congruent $ \triangle CEF \cong \triangle DEB$ because ASA $ \angle DBE \cong \angle CFE$ because corresponding parts of congruent triangles are congruent $ \triangle CEF \cong \triangle CEB$ because SSS
Explanation: Try going through the proof yourself: write down the givens, and then see if they justify the next step for the reason given. Then do the same thing for the next step, and the next, until you run into something that you can't justify, or you finish the proof. $ \overline{CF} \cong \overline{AF}$ is the first wrong statement.